1. Field of the Invention
The present invention concerns an apparatus for radiographic image acquisition, having a radiation source with an associated laser device to display a linear light marking on the examination subject for alignment of the subject relative to the radiation source for a subsequent image acquisition.
2. Description of the Prior Art
In the acquisition of radiographic images, for example x-ray images, the precise alignment of the patient relative to the radiation source (the x-ray radiator) is very important so that the correct examination region is acquired by the radiation image and the patient is not exposed unnecessarily frequently to the radiation due to erroneous positioning. For alignment purposes, in order to make the body region irradiated by the x-ray radiation recognizable in a subsequent image exposure, in the prior art a light-beam localizer is used in which light generated by a strong halogen lamp having a power of more than 100 watts is projected on the patient. A disadvantage of such a light-beam localizer is that the halogen lamps frequently burn out due to significant heating. A further disadvantage is that, in the case of the radiation image acquisition apparatus being in a room with strong ambient brightness (such as, for example, in an operating room), the projected light field is only very poorly visible due to the ambient brightness.
As an alternative to the halogen light-beam localizer, the use of a laser-line light-beam localizer is known in which a narrow laser line is superimposed on the patient by means of a laser in the center of the expected x-ray beam field. This laser-line light-beam localizer namely allows a positioning of the patient without having to activate x-ray radiation for this purpose. Due to the fact that lasers that can be aimed on humans may not exceed a specific low power, the resulting laser line projection is relatively weak. Problems result from this when the laser light line is projected in brightly illuminated spaces, since it only visible with great difficulty.